Run-length encoding: Difference between revisions

=={{header|ed}}==

An important limitation: only handles repetitions of up to 9 times. Extending the algo for more is trivial, but beyond this example.

<syntaxhighlight lang="sed">

H

,p

g/\([a-zA-Z]\)\1\1\1\1\1\1\1\1/s//9\1/g

g/\([a-zA-Z]\)\1\1\1\1\1\1\1/s//8\1/g

g/\([a-zA-Z]\)\1\1\1\1\1\1/s//7\1/g

g/\([a-zA-Z]\)\1\1\1\1\1/s//6\1/g

g/\([a-zA-Z]\)\1\1\1\1/s//5\1/g

g/\([a-zA-Z]\)\1\1\1/s//4\1/g

g/\([a-zA-Z]\)\1\1/s//3\1/g

g/\([a-zA-Z]\)\1/s//2\1/g

,p

g/9\([a-zA-Z]\)/s//\1\1\1\1\1\1\1\1\1/g

g/8\([a-zA-Z]\)/s//\1\1\1\1\1\1\1\1/g

g/7\([a-zA-Z]\)/s//\1\1\1\1\1\1\1/g

g/6\([a-zA-Z]\)/s//\1\1\1\1\1\1/g

g/5\([a-zA-Z]\)/s//\1\1\1\1\1/g

g/4\([a-zA-Z]\)/s//\1\1\1\1/g

g/3\([a-zA-Z]\)/s//\1\1\1/g

g/2\([a-zA-Z]\)/s//\1\1/g

,p

Q

</syntaxhighlight>

{{out}}

<pre>$ ed -s run-length.input < run-length.ed

Newline appended

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aaaaahhhhhhmmmmmmmuiiiiiiiaaaaaa</pre>